This is clearly unbiblical teaching. The Bible teaches grace comes through the Lord Jesus Christ. Mary is never mentioned in the Bible as bestowing grace. Grace can only come from God and His Son.
If you don’t believe me, read the whole New Testament for your self and then decide.
4 I thank my God always on your behalf, for the grace of God which is given you by Jesus Christ;
5 That in every thing ye are enriched by him, in all utterance, and in all knowledge;
6 Even as the testimony of Christ was confirmed in you:
1Co 1:3 Grace be unto you, and peace, from God our Father, and from the Lord Jesus Christ.
1Co 1:4 I thank my God always on your behalf, for the grace of God which is given you by Jesus Christ;
In fact, she is barely mentioned at all. Doesnt seem like much time is devoted to her sinlessness, perpetual virginity, Queen of Heaven status, bodily assumption, etc.
Catholics cannot use the Bible to support these doctrines because they are not taught anywhere ... At best they were made up by men ... at worst by the Angel of Light.